Introduction to Database
Lec 01
Dr Adel Khaled
Outlines
• BASIC CONCEPTS AND DEFINITIONS
• Data Versus Information
• Metadata
• TRADITIONAL FILE PROCESSING SYSTEMS
• Data Models
• Database Management Systems (DBMS)
• COMPONENTS OF THE DATABASE ENVIRONMENT
• Characteristics of the Database Approach
BASIC CONCEPTS AND DEFINITIONS
BASIC CONCEPTS AND DEFINITIONS
BASIC CONCEPTS AND DEFINITIONS
➢ Data Historically, the term data referred to facts concerning objects and events that could
be recorded and stored on computer media.
➢ For example, in a salesperson’s database, the data would include facts such as customer
name, address, and telephone number.
➢ This type of data is called structured data.
➢ The most important structured data types are numeric, character, and dates.
➢ Structured data are stored in tabular form (in tables, relations, arrays, spreadsheets, etc.)
and are most commonly found in traditional databases and data warehouses.
BASIC CONCEPTS AND DEFINITIONS
Databases today are used to store objects such as documents, e-mails, maps,
photographic images, sound, and video segments in addition to structured data.
For example, the salesperson’s database might include a photo image of the
customer contact.
This type of data is referred to as unstructured data, or as multimedia data.
Data Versus Information
These facts satisfy our definition of data, but most
people would agree that the data are useless in
their present form. Even if we guess that this is a
list of people’s names paired with their Social
Security numbers, the data remain useless
because we have no idea what the entries mean.
Data Versus Information
Metadata
• Metadata are data that describe the properties or characteristics of end- user data and
the context of that data.
• Some of the properties that are typically described include data names, definitions,
length (or size), and allowable values.
• Metadata describing data context include the source of the data, where the data are
stored, ownership (or stewardship), and usage.
• Although it may seem circular, many people think of metadata as “data about data.”
Metadata
TRADITIONAL FILE PROCESSING SYSTEMS
• When computer-based data processing was first available, there were no databases
• As business applications became more complex, it became evident that traditional file
processing systems had a number of shortcomings and limitations.
TRADITIONAL FILE PROCESSING SYSTEMS
Disadvantages of File Processing Systems
➢ PROGRAM-DATA DEPENDENCE File descriptions are stored within each database application
program that accesses a given file.
➢ DUPLICATION OF DATA Because applications are often developed independently in file
processing systems, unplanned duplicate data files are the rule rather than the exception.
➢ LIMITED DATA SHARING With the traditional file processing approach, each application has its
own private files, and users have little opportunity to share data outside their own applications..
➢ Managers often find that a requested report requires a major programming effort because data
must be drawn from several incompatible files in separate systems.
➢ EXCESSIVE PROGRAM MAINTENANCE The preceding factors all combined to create a heavy
program maintenance load in organizations that relied on traditional file processing system.
Data Models
Data models capture the nature of and relationships among data and are used at different
levels of abstraction as a database is conceptualized and designed.
The effectiveness and efficiency of a database is directly associated with the structure
of the database.
Entity A person, a place, an object, an event, or a concept
in the user environment about which the organization
wishes to maintain data.
Attribute: The data you are interested in capturing about the
entity (e.g., Customer Name) is called an.
Data Models
RELATIONSHIPS A well-structured database establishes the relationships between entities
that exist in organizational data so that desired information can be retrieved.
Most relationships are one-to-many (1:M) or many-to-many (M:N)
Database Management Systems (DBMS)
Database management system (DBMS) A software
system that is used to create, maintain, and provide
controlled access to user databases.
in Figure 1-4 there is only one place where the
CUSTOMER information is stored rather than the
two Customer Master Files. Both the Order Filling
System and the Invoicing System will access the
data contained in the single CUSTOMER entity.
File system
DBMS
Advantages of the Database Approach
Cautions About Database Benefits
COMPONENTS OF THE DATABASE
ENVIRONMENT
• Computer-aided software engineering (CASE) tools
CASE tools are automated tools used to design
databases and application programs.
• These tools help with creation of data models and
in some cases can also help automatically
generate the “code” needed to create the
database.
COMPONENTS OF THE DATABASE
ENVIRONMENT
❑ Repository A repository is a centralized knowledge base for all data definitions, data relationships,
screen and report formats, and other system components.
❑ A repository contains an extended set of metadata important for managing databases as well as
other components of an information system.
❑ DBMS A DBMS is a software system that is used to create, maintain, and provide controlled access
to user databases.
❑ Database A database is an organized collection of logically related data, usually designed to meet
the information needs of multiple users in an organization. It is important to distinguish between
the database and the repository. The repository contains definitions of data, whereas the database
contains occurrences of data.
COMPONENTS OF THE DATABASE ENVIRONMENT
➢ Application programs Computer-based application programs are used to create and maintain
the database and provide information to users.
➢ User interface the user interface includes languages, menus, and other facilities by which users
interact with various system components, such as CASE tools, application programs, the DBMS,
and the repository.
➢
Data and database administrators Data administrators are persons who are responsible for the
overall management of data resources in an organization. Database administrators are
responsible for physical database design and for managing technical issues in the database
environment.
➢
System developers System developers are persons such as systems analysts and programmers
who design new application programs. System developers often use CASE tools for system
requirements analysis and program design.
Database Applications
• These examples are what we called traditional database applications
• More Recent Applications:
• Traditional database application
• Geographic Information Systems (GIS):can store and analyze maps, weather data,
and satellite images
• Multimedia database: store images, audio clips, and video streams digitally
• Data Warehouses: systems are used in many companies to extract and analyze useful
business information from very large databases to support decision making.
• Real-time and active database technology is used to control industrial and
manufacturing processes.
• Database search techniques are being applied to the World Wide Web to improve the
search for information
Database can be any size and complexity
For example:
• A list of names and address
• IRS Internal Revenue Service
(assume it has 100 million taxpayers and each taxpayer file 5 forms with 400
characters of information per form=800Gbyte)
• Amazon.com
(15 million people visit per day; about 100 people are responsible for
database update)
An UNIVERSITY Example
• A UNIVERSITY database for maintaining information concerning
students, courses, and grades in a university environment
An UNIVERSITY Example
STUDENT file stores data on each student
COURSE file stores data on each course
SECTION file stores data on each section of each course
GRADE_REPORT file stores the grades that students receive
PREREQUISITE file stores the prerequisites
An UNIVERSITY Example
Database manipulation involves querying ‫ االستعالم‬and updating. Examples of queries are as
follows:
•
Retrieve the transcript—a list of all courses and grades—of ‘Smith’
•
List the names of students who took the section of the ‘Database’ course offered in fall 2008
and their grades in that section
•
List the prerequisites of the ‘Database’ course
Examples of updates include the following:
•
Change the class of ‘Smith’ to sophomore
•
Create a new section for the ‘Database’ course for this semester
•
Enter a grade of ‘A’ for ‘Smith’ in the ‘Database’ section of last
semester
Characteristics of the Database Approach
The main characteristics of the database approach
Self-Describing Nature of a Database System
➢ A fundamental characteristic of the database approach is that
the database system contains not only the database itself but
also a complete definition or description of the database
structure and constraints.
➢ This definition is stored in the DBMS catalog, which contains
information such as the structure of each file, the type and
storage format of each data item, and various constraints on
the data.
➢ The information stored in the catalog is called meta-data
Characteristics of the Database Approach
➢ Support of Multiple Views of the Data
➢ A database typically has many types of users, each of whom
may require a different perspective or view of the database.
➢ A view may be a subset of the database or it may contain
virtual data that is derived from the database files but is not
explicitly stored.
➢ Some users may not need to be aware of whether the data
they refer to is stored or derived.
➢ A multiuser DBMS whose users have a variety of distinct
applications must provide facilities for defining multiple
views.
Characteristics of the Database Approach
Sharing of Data and Multiuser Transaction Processing
• A multiuser DBMS, as its name implies, must allow multiple users to access the database at the
same time.
• This is essential if data for multiple applications is to be integrated and maintained in a single
database.
• The DBMS must include concurrency control software to ensure that several users trying to
update the same data do so in a controlled manner so that the result of the updates is correct.
• A fundamental role of multiuser DBMS software is to ensure that concurrent transactions operate
correctly and efficiently.
Database Users
Database administrators:
Responsible for authorizing access to the database, for coordinating and monitoring its use,
acquiring software and hardware resources, controlling its use and monitoring efficiency of
operations.
Database Designers:
Responsible to define the content, the structure, the constraints, and functions or transactions
against the database. They must communicate with the end-users and understand their needs.
End Users
Access to the database for querying, updating, and generating reports
System Analysts
Determine the requirements of end users